Condenser and process of making same.



No. 825,405. PATENTED JULY 10, 1906.

M. K. McGRATH. CONDENSER AND PROCESS OF MAKING SAME.

APPLIOLTIDR FILED NOV. 28. 1902.

' then fol UNITED STATES PATENT OFFIOE.

MAURICE K. Mo GRATH, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC MPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

CONDENSER AND PROCESS- OF MAKING SAME.

Specification of Letters Eatent.

- Patented July 10, 1906.

Applioatimi filed November 28, 1902. Serial No. 33,014.

To all whom it may concern.-

Be it known that I, MAURICE K. MCGRATH, a citizen of the Unitedv States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Condensers and Processes of Making the Same, of which the following is a full, clear, concise, and exact description.

My invention relates to a condenser and process of making the same and its object is to produce an improved condenser which shall be extremely compact, of small .dimensions, andcheap to manufacture, while possessing increased efliciency, permanence, and durability.

In accordance With my invention I preferably first assemble the strips of foil and paper by rollin them together upona fiat arbor,

shape or complete zigzag, and finally, after having boiled the folded condenser in melted parafiin-wax or the like, I sub'ect it to pressure on all sides in a mold, while allowing the wax to cool and set. denser in the form of a prism may be inclosed in a suitable metal case for protection and to prevent it from unfolding.

I will describe my invention particularly by reference to the accompanying'drawings, and that which I consider to be novelwith mewill be pointed out-broadly in the ap; pended claims.

Figure 1 is a perspective view illustrating the paper and tin-foil strips assembled in a fiat roll. Fig. 2 shows this roll reversely folded into an S shapeand placed inthe square mold, in which it is to be boiled in paraffin and finally pressed. Fig. 3 shows the pressing operation. Fig. 4 is a view of the condenser after pressing, and Fig. 5 shows the same inclosed in its protecting tin case.

Similar letters of reference are used to designate the same parts wherever shown.

It has been usual heretofore in making con densers to roll up four sheets of paper a and two sheets of tin-foil a of the required width into'a flat roll a, as shown in Fig. 1, this roll then being boiled in parafiin and pressed flat on two sides. Condensers have also been made by rolling the flat roll into substantially cylindrical shape and inclosing the same directlyin a cylindrical case Without pressure;

this fiat roll "reversely into an S The completed con-v but in accordance with my invention the flat roll a is folded reversely into an S shape, as shown in Fig. 2, and placed in the rectangular mold or trough b, with the doubled ends of the roll at the top and bottom. A rectangu lar wooden block (1 is then placed in the trough on top of the roll a and the whole boiled for, say, two or three hours in melted paraffin. After the boilin a number of the troughs containing the fol ed condensers are placed side by side in a press c and pressure applied to top and bottom,forcing the blocks.

(1 downward into the troughs or molds in the manner of plungers, so that the folded roll is compressed in the bottom of the trough and subj ected,in eifect,to pressure on all four sides. The pressure is maintained until the paraffin has thoroughly hardened, after which the co'ndenser appearing as shown in Fig. 4, is removed and finally placed in its tin protecting-case e, as shown in Fig. 5. Said case is constructed and sealed in a manner to hold the condenser tightly and prevent the leaves from separating.

A condenser of twomicrofarad capacity can be made, as above described, in the form of a prism an inch and a half square and four inches long, while a condenser of the same capacity, made accordingto the old plan, would be twice as long, twice as wide, and a third as thick, using twice the material and costing, approximately, twice as much as mine. The increased capacity with a given amount of material in my condenser is probably due to the fact that the pressure upon thefolded roll forces the leaves into much more intimate contact with one another. The capacity of an ordinary fiat condenser is liable to become reduced with age, due to the separation of the leaves; but in my folded form this will not be so liableto happen, because the leaves cannot separate to any appreciable extent-without a straightening out of the folds, which is of-course prevented by the inclosing case. There are many ways in which the paper strips may be folded into a square form; but I prefer the S-shaped fold, because here the laminae are nearly all of equal length and there is less tendency for the foil to wrinkle and separate than in the other forms. In general the distortion of the laminae and displacement at the ends may be prevented by reversely folding the fiat roll two times or any multiple of two times;

but a complete zigzag fold, whether two 01. more times, is desirable.

Having described my invention, I claim 1. The herein-described process of making condensers, which consists in assembling the strips of foil and insulating material in a fiat roll, folding said flat roll, treatin the same with melted wax or the like, and ally sub-.

jecting the folded roll to continual pressure on all sides while allowing the wax to cool and set.

2. The herein-described process of making condensers, which consists in assembling strips of foil and paper in a fiat roll, reversely folding the flat roll into an S shape, treating the {same with melted paraflin-wax or the like, placing the folded roll in a narrow rec'- 4. A condenser comprising a fiat roll of and tin-foil, assemble melted wax, an sure on all sides in amold while allowing the strips of foil and paper reversely folded a complete zi zag, paraflined, and pressed.

5. A condenser com rising strips of paper and folded reversely intoen shape,- and finally pressed on four sides, the pressure being sufficient to produce intimate contact between the strips of foil and insulating material where the same are folded.

6. The herein-described process of making condensers, which consists in rollingand folding strips of paper and tin-foil reversely into an S k sha e, treating the same with rfsubjecting the same to preswax to cool and set, the pressure being applied in such a way as to force all adjacent portions of said strips into intimate relation; whereby maximum capacity for a given amount of material is obtained.

In witness whereof I hereunto subscribe my name this 13th day of September, A. D. 1902.

MAURICE K. MOGRATH.

Witnesses:

DE WITT O. TAN ER, GEORGE P. BARTON. 

